| 摘要 |
<p>This invention concerns intermediates for use in preparing beta -lactam antibiotics. More specifically the invention provides a compound of the formula <IMAGE> wherein R1 is hydrogen or acyl or the group R1-NH- is protected amino; R3 and R4 are the same or different and each is hydrogen, alkyl, cycloalkyl, phenyl or substituted phenyl, or one of R3 and R4 is hydrogen and the other is alkoxycarbonyl, alken-1-yl, alkyn-1-yl, 2-phenylethenyl or 2-phenylethynyl; V is a leaving group; and M<+> is hydrogen or a cation. It also provides similar compounds where R1 is a protecting group.</p> |
